Antibiotic residues in the raw and pasteurized milk produced in Northeastern Iran examined by the four-plate test (FPT) method.

The antibiotic residues were investigated in raw and pasteurized milk produced in Neyshabur region, Iran. To this end, 82 milk samples, including raw and pasteurized milk of different brands and local raw milk samples of collection centers, were collected from Neyshabur region in two seasons during 2016. The antibiotic four-plate test (FPT) was performed to examine the presence of tetracycline, flomocaine, sulfonamide, enrofloxacin, aminoglycoside, and macrolide in the samples. The data were analyzed by the chi-squared test and logistic regression analysis to determine significant differences among variables at the significance level of p < .05. The results revealed that, among the 82 milk samples, 16 (47.2%) collected raw milk, 10 (41.6%) raw milk in the factories, and 6 (25%) pasteurized milk samples were positive. The findings showed that the most positive antibiotics belonged to the flomocaine, tetracycline, sulfonamide, and enrofloxacin groups, respectively. However, no aminoglycoside or macrolide was found in the samples. Analysis of milk samples performed in two seasons and the site of the sample collection showed a significant difference in the antibiotic residue content (p < .05). Logistic regression analysis showed that the odds of contamination in winter were 3.73 times that of fall (p = .006). Positive antibiotic residues were present in a large number of milk samples. This study highlights the need for special measures and effective monitoring programs to reduce the hazard of chemical contamination in the Neyshabur region. [ABSTRACT FROM AUTHOR]